1. Field of the Invention
This invention pertains to a two-cycle marine engine equipped with a separate, lubricating system. The lubricating system is designed to assure that air/charge flow control valves and their associated bearings in the engine carburetor are adequately lubricated and protected from corrosion.
2. Discussion of the Prior Art
When used in salt water environments, marine engines are subjected to the corrosion effects of salt. One particular corrosion problem occurs when the salt enters the air intake of the carburetor and adheres to the rotating choke plate valve or the throttle plate valve of the carburetor or their respective bearings. This corrosion effect can occur even when the engine is not running.
A previously proposed solution to this problem of preventing salt from adhering to and corroding carburetor valves is disclosed in Japanese Patent Publication No. Sho 64-32010. This solution involved locating lubrication oil injector openings upstream of the throttle or choke valves in the air intake passage of the carburetor. The injected oil functioned to lubricate the throttle or choke valve and to prevent salt adhesion to these valves. In this prior disclosure the lubricant oil would be joined with the fuel and air charge entering the combustion chambers of the engine and would additionally lubricate the crankshaft bearings and pistons.
This previous proposal was found to provide excellent results in preventing salt adhesion to air/charge flow control valves when compared with other prior art lubricating arrangements which are located in the oil injectors downstream of the carburetor. However, since the injectors were located in the center of the air intake passage, there were cases when a sufficient amount of oil would not reaching the bearings on either side of the throttle or choke plate valves, particularly when only small amounts of oil were being injected such as when the engine was running at low speeds. Therefore, if an engine with such a lubrication system operated for long periods of time at low speeds and then was turned off without first revving it up to a higher speed, salt deposits would accumulate on the valves and their associated bearing, causing eventual corrosion and sticking of the valves.
An additional problem exists in small marine crafts, such as jet skis, since these crafts generally tip onto their sides during operation thereby causing sea water to enter the engine compartment. The salt in the sea water entering the engine compartment could adhere to air/charge control valves of the engine and cause sticking. When sticking of the throttle valve occurs, it can be difficult to control engine acceleration and deceleration; when salt adheres to the choke valve, cold starting becomes a problem.